Innate & Adaptive Immune Responses

The innate immune system initially recognizes pathogens via both the complement system and pattern recognition receptors. The complement system, also part of humoral immunity, is a family of proteins that recognize and bind pathogens, marking them for phagocytosis. Pattern recognition receptors include 3 families of receptors (toll-like, NOD-like, and RIG-I-like), each of which initiate the type I interferon response upon activation by specific pathogen classes. This interferon response activates adaptive immunity, a major part of cell-mediated immunity including B cells and T cells. The conclusion of adaptive immunity results in memory T cells, which express receptors for antigens, and memory B cells, which produce antibodies to recognize pathogens. These cells allow the adaptive immune system to mount a stronger response upon the next exposure to the pathogen. Innate and adaptive immunity were originally thought to be two separate arms of the immune system. However, recent studies show cross-talk between these 2 immune responses. For example, dendritic cells and natural killer cells are thought to link the innate and adaptive immune responses. These cells show the nonspecific responses to pathogens of the innate immune system, but are also involved in the activation of T and B cells, part of adaptive immunity. Immune responses require activation of a complex series of pathways. Disruption of these processes can lead to inhibition of immune cell activation, increasing susceptiblity to infection. However, immune system dysfunction can also lead to excessive activation, such as mast cell hyperstimulation during allergic responses, or the broad immune system activation caused by septic shock. Studies of both the innate and adaptive immune processes are necessary to define how these pathways cross-talk, and identify targets for inhibition of immune cell dysfunction. ...

Read more

The innate immune system initially recognizes pathogens via both the complement system and pattern recognition receptors. The complement system, also part of humoral immunity, is a family of proteins that recognize and bind pathogens, marking them for phagocytosis. Pattern recognition receptors include 3 families of receptors (toll-like, NOD-like, and RIG-I-like), each of which initiate the type I interferon response upon activation by specific pathogen classes. This interferon response activates adaptive immunity, a major part of cell-mediated immunity including B cells and T cells. The conclusion of adaptive immunity results in memory T cells, which express receptors for antigens, and memory B cells, which produce antibodies to recognize pathogens. These cells allow the adaptive immune system to mount a stronger response upon the next exposure to the pathogen. Innate and adaptive immunity were originally thought to be two separate arms of the immune system. However, recent studies show cross-talk between these 2 immune responses. For example, dendritic cells and natural killer cells are thought to link the innate and adaptive immune responses. These cells show the nonspecific responses to pathogens of the innate immune system, but are also involved in the activation of T and B cells, part of adaptive immunity. Immune responses require activation of a complex series of pathways. Disruption of these processes can lead to inhibition of immune cell activation, increasing susceptiblity to infection. However, immune system dysfunction can also lead to excessive activation, such as mast cell hyperstimulation during allergic responses, or the broad immune system activation caused by septic shock. Studies of both the innate and adaptive immune processes are necessary to define how these pathways cross-talk, and identify targets for inhibition of immune cell dysfunction.